The present invention relates a printing apparatus and an information processing apparatus using the printing apparatus and, more particularly to a printing apparatus and an information processing apparatus such as DTP (Disc Top Publishing), CAD (Computer Aided Design), EP (ElectroPhoto Publishing) and a photo-filing apparatus using the printing apparatus.
In the present invention, the printing apparatus such as LBP (Laser Beam Printer) controls a dot printing element in accordance with an image information signal and forms a visual image which is expressed using dots. The laser beam printer comprises a main control circuit for controlling the dot printing element which is transmitted from an image information signal generating unit.
The image information signal generating unit employs an image data read-out apparatus for generating a gradation data signal of an image to be printed, a personal computer and a word processor for generating a character pattern dot signal and an image information signal generating unit being combined the above stated apparatuses together with. The image information signal generating unit outputs a gradation information signal and in accordance with an inputted gradation information signal a printing dot size control and a dither matrix control are carried out, respectively.
In the image data for printing the image in the conventional printing apparatus for use in this kind of the information processing apparatus, in a case that a picture expressing a gradation is printed, the image data is converted to a dither matrix data at a side of an image information signal generating unit and a dot signal which has been converted as a two-valued logic is given at a side of the printing apparatus.
The dither matrix used generally for the gradation expression is rough as the image, for example so as to express 64 stage gradations even the expression of a half tone comprises 64 gradations because a dot matrix having 8.times.8 is expressed as one unit. Further in a case that the gradation expression such as 128 stage gradations and 256 stage gradations is intended to express, the image becomes more roughly because the size of the picture element or the expression size of photograph becomes large.
Besides, for expressing the above stated gradations, for example in a case that 64 stage gradations are expressed by varying the size of the dot constituting the image, there are many technical problems for obtaining the good reproduction in the dot size.
For solving the above stated various technical problems, the printing apparatus is disclosed in Japanese Patent Laid-Open No. 61566/1986, for example. In this conventional printing apparatus, the gradation information signal is inputted through the image information signal generating unit and in accordance with the gradation information signal both the printing dot size control and the dither matrix control are carried out.
It is desirable to connect the printing apparatus to the various kind of the image information signal generating units and to print the various kinds of the image data which are given through the image information signal generating units. However, there has been not paid an attention about the above stated consideration in the conventional printing apparatus.